Description

Some effects, like the fragment shader based effects, can only use GL
textures, and in order to apply those effects to any kind of actor they
require that all drawing operations are applied to an offscreen framebuffer
that gets redirected to a texture.

ClutterOffscreenEffect provides all the heavy-lifting for creating the
offscreen framebuffer, the redirection and the final paint of the texture on
the desired stage.

clutter_offscreen_effect_get_texture ()

Retrieves the texture used as a render target for the offscreen
buffer created by effect

You should only use the returned texture when painting. The texture
may change after ClutterEffect::pre_paint is called so the effect
implementation should update any references to the texture after
chaining-up to the parent's pre_paint implementation. This can be
used instead of clutter_offscreen_effect_get_target() when the
effect subclass wants to paint using its own material.